I have been wearing this model of socks since the 1990s. I had several pairs which all lasted me well over five years, and maybe some closer to ten years. I wore them with my military uniform boots when I was enlisted, so they got used daily. Since I got out of the military in 2009, for some reason I started buying other brands of socks to fulfill the same role (probably sometimes because they were cheaper and sometimes because of availability; it is not common to come across these in stores, especially in New Mexico where I currently live). It was a total mistake to bother with other brands. I've bought REI branded socks, SmartWool, and Darn Tough, among other, cheaper brands, and none of them have come close to the comfort and longevity of these Thorlos. I am still employed in a job where I have to wear duty boots daily, so I spend a lot of time in heavy socks and on my feet. Again: nothing else compares to these. No other socks I've tried are better than 60% as good as these, all-around. I wear wool socks almost exclusively for their comfort in all seasons, anti-bacterial and wicking properties, thermo-regulation and general comfort and contribution to foot health. I wear thinner socks with my shoes and hiking boots and really heavy socks with my duty boots, but all wool. • Why these are the best socks I've ever worn with duty boots: —These are extremely thickly padded in the toe and heel, and supportive through the arch. This reduces fatigue in my feet during long periods of walking and standing. —They stay up: I have very large calves and the tops of shorter socks stop on the downward taper of my calf muscles and are naturally pushed down by the movement of my calves when I walk, so I constantly have to pull them up throughout the day. BUT, socks that are this tall from other brands still shimmy down my leg because the elastic at the top is insufficient to keep them in place; especially SmartWool and REI brand socks, which have a small (about 1/2 inch wide) band around the top that digs in and leaves an itchy ring by the end of the day. The Darn Tough socks stay put, but they're so tall I have to fold the top over and if I don't get it just right, they'll slide down, too. These Thorlos have a wide elastic band that holds them in place all day, requiring very little to no fussing with. —The yarn inside these is very tightly and densely knit or woven (not sure which) as are the Darn Tough socks. The insides of SmartWool socks are much looser, meaning that there is nowhere near as much padding or insulation, and they wear out much quicker. The REI socks are more dense than SmartWool but less so than these, with corresponding longevity. • Special care/washing Thorlo recommends that these be washed with fabric softener (not dryer sheets), claiming that they're more comfortable and last longer. I have found this to be true in my experience. I've seen complaints about this in reviews in the past, but it is a minor issue for me; I find it to be well worth the effort and time to have superior performance from the socks. • In conclusion, these are the best heavy socks I've ever worn, hands down. I will not be messing around with any other brands because they're available at a local store, or they're on clearance for less than half of what I paid for these. It's not worth it. Theese are expensive. I have to order them. Well, that's what I'll be doing. I recently bought one pair of these and I will be buying one or two pairs a month until I've replaced all of my other socks, and those others will be relegated to the storage for emergencies or to give to someone in need of heavy socks in a pinch. • Thank you for taking the time to read this, if you've gotten this far. I hope this was helpful to you in making a decision about your sock purchase.